This document contains the list of standards related to various types of bearingsFull description
An active magnetic bearing (AMB) system is a collection of electromagnets used to suspend an object and stabilization of the system is performed by feedback control. The system is composed of a flo...
Design of piers and pier cap. Abutments, and bearings
network simulator Graphical tool
Introduction and Conclusion
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About the LTE and its features
Design of piers and pier cap. Abutments, and bearings
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TO THE WORLD OF
BEARINGS
A bearing is a machine element which reduces friction between two two members, having having relative motion with respect to each other.
A bearing is a machine element which reduces friction between two two members, having having relative motion with respect to each other.
• To provide rigidity to the shaft in axial and
radial direction. • To reduce friction and wear out of
components, which are having relative re lative motion. Thereby, reducing the heat and sound generated. consider able speeds • To carry loads at considerable
Bearing Geometry Bearing length,L Housing Bearing Shaft / Journal Bearing dia., D b
Journal dia., D j
Types of bearings
Sliding Contact Bearings or Frictional Bearings
Rolling Contact Bearings or AntiFriction Bearings
Rolling Contact Bearings Ball Bearings
Roller Bearings
ROLLING BEARINGS BALL BEARINGS
s g n i r a e b l l a b e v o o r g p e e
s g n i r a e b l l a b g n i n g i l a f l e
l l a b t c a g t n n i o r c a r e a b l u g n A
ROLLER BEARINGS
s g n i r a e b l l a b t s u r h T
s g n i r a e b r e l l o r l a c i r d n i l y
s g n i r a e b r e l l o r l a c i r e h p S
s g n i r a e b r e l l o r r e p a T
s g n i r a e b r e l l o r e l d e e N
FRICTIONAL BEARINGS ARE OF TWO TYPES 1.
BUSH BEARINGS
2. SLIDE
OR
SLEEVE BEARINGS (ex. Journal bearing)
FEATURES OF JOURNAL BEARINGS
JOURNAL BEARINGS ARE OF HYDRO DYNAMIC FILM OPERATED TYPE THESE ARE HIGH CAPACITY LOAD BEARING TYPE THERE IS NO CONTACT BETWEEN MOVING & NON MOVING ELEMENTS USES BABBIT METAL AS BEARING MATERIAL
Types of Bearings Single-row Radial Ball
Angular Contact Ball
Radial Roller
Angular Roller
Types of Bearings Tapered Roller Spherical Roller
Thrust Roller Needle roller
Deep Groove Ball Bearings
Self Aligned Ball Bearings
Taper roller bearings CUP
CONE
Ball Bearings Detailed View
BEARING LIFE Life of a bearing is defined as the number of revolutions which the bearing is capable of enduring before the first sign of fatigue (flaking, spalling and crack) occurs on one of its ring or rolling element
Bearing Rated Life Test (fatigue) data Radial Load (lbs)
Empirical relationship:
P 1 L1 P 2
L2
k
•k=3.0 (ball) •k=3.33 (roller)
P1=Basic dynamic rated load, N P2=Equivalent dynamic load, N
L10 Life (cycles)
Bearing Selection
Determine the design life (in cycles) Determine the design load P d = V R
V=1 for inner race rotation V=1.2 for outer race rotation
Calculate the required basic dynamic load 1
Ld k C req'd P d 6 10 Select a bearing with (C > Creq’d) and a bore that closely matches the shaft diameter.
Bearing Operation Boundary Lubrication
F
n
The oil fills in the volume in the troughs on the mating parts. There is extensive metal-to-metal contact of the peaks and a high rate of friction and wear.
Bearing Operation Full-film Lubrication Lubricant
F
n
As the shaft rotates, the oil sticks to the surface of the shaft and a thin film is established between the bearing and the rotating shaft. There is no metal-to-metal contact and the shaft appears to float above the bearing.
Bearing Lubrication The Functions of Lubrication • Lubricants reduce wear and friction by – Lubricating all true rolling contacts elastohydrodynamically – Lubricating sliding contacts between the raceways and rolling elements – Lubricating sliding contact between the rollers and guiding elements
The Functions of Lubrication •
Lubricants also – Protect highly finished surfaces of rolling elements and rings from corrosion – Help prevent intrusion of foreign matter, (done with grease pack) – Provide a heat transfer medium
Lubricant Selection Base Oil viscosity VISCOSITY = "resistance to flow" of a fluid
Water: low viscosity (1cSt at 20°C)
Honey: high viscosity (~1200 cSt at 20°C)
Lubricant Selection Base Oil viscosity low viscosity:
high viscosity:
+ low friction - thin oil film
+ thick oil film - high friction
Finding the right balance
base oil viscosity changes with temperature ! (like with honey)
Lubricant Selection Definition of Grease A grease is 90 % oil held in a thickener (10 %)
Think of the thickener as a sponge holding the oil
It is not: – a thick oil – a solid oil (wax)
Lubricant Selection What's inside a grease? Grease =
Base oil (70-95 %)
+
Thickener (5-30 %)
GRE ASELGMT3/180 Ga r sa G re a s e
Fet t G ra ss o
Ga r sse i
+
Additives n t s a x i d o i t r s A n o t i b n h i I t u s R e a r w i t d a n n a i v e s E P a d d i t
How do Bearings Fail? Not always due to Natural Causes Only
34 of bearings fail due to Fatigue, which is the basis of life calculation.
%
How do Bearings Fail? Poor Lubrication
is the reason for
36 of premature bearing failures
%
How do Bearings Fail? Contamination is the reason for
14 of premature bearing failures
%
How do Bearings Fail? Poor Installation
is the reason for
16
%
of premature bearing failures
Bearing Failures & Their Causes Unusual operating behaviour indicating damage :Subjective damage recognition In the vast majority of bearing applications it is sufficient when machine operators watch out for uneven running or unusual noise in the bearing system
Bearing F ailures & Their Causes Unusual operating behaviour indicating damage : Subjective damage recognition Symptoms
Uneven running
Sources of Trouble
Examples
Damaged ring or rolling elements
Motor vehicles: * More and more wheel wobbling * Increased tilting clearance * Vibration of steering system
Contamination
Fans: * Growing vibration
Excessive bearing clearance
Saw Mills : * More knocks and blows on connecting rods
Bearing F ailures & Their Causes Unusual operating behaviour indicating damage : Subjective damage recognition Symptoms
Reduced working accuracy
Sources of Trouble
Examples
Wear due to * Contamination or * Insufficient Lubrication
Lathe: * Gradual development of chatter marks on work piece
Damaged rings or rolling elements
Grinders: * Weavy ground surface
Change in adjustment: * Clearance or * Preload
Cold Rolling Mills : * Periodic surface defects on rolled material e.g., stretcher strains or ghost lines
Bearing F ailures & Their Causes Unusual operating behaviour indicating damage : Subjective damage recognition Symptom s
Unusual Running Noise
Sources of Trouble
Whinning or Squealing noise
Insufficient operating clearance
Rumbling or Irregular noise
Excessive Clearance Damaged contact areas Contamination Unsuitable Lubricant
Gradual change in running noise
Change in operating clearance due to temperature Damaged running track due to contamination or fatigue
Examples
Electric Motors Gears
DOs & DON’Ts with Bearings DO s •.Keep the bearings in protective packing till they are mounted. •.Cover the assembled bearings appropriately to avoid dust ingress. •.Store the bearings in dry area. •.Use tubes, Pullet, Hydraulic nuts, and other tools for removal / fixing of the bearings. •.Use correct amount of specified lubrication at right time in correct procedure.
DOs & DON’Ts with Bearings DO’s •Prevent the penetration of external contaminants into the bearings. •Maintain the fits between the bearings with mating shaft / housing. •Align the members properly to avoid unnecessary load on the bearings. •Check the operating condition of the bearings by feeling the noise, temperature and sensing vibration through touch. •Fill the bearings with right grease while assembling .
DOs & DON’Ts with Bearings Dont’s •Over lubrication is a silent killer for bearings. Do not over lubricate. • Never allow welding at bearings that will damage the contact surfaces. •Do not apply direct blows on the bearing while mounting / dismantling. •Do not keep the bearings in a dusty area. •Don’t let the bearing stand upright, store them flat on their sides.
DOs & DON’Ts with Bearings Dont’s •Do not allow water to enter the bearings / lubricant. •Do not use water to clean the bearings.
